I have made custom level editors on both and even if there is no ini plugin on C2, JSON files are faster anyways so I don't miss that anymore. Recently I figured out how to use external audio files on C2 so that is no problem (very easy in the end).
Stuff I would like to have from CC to C2 at the moment are mainly image offset and maybe performance on some cases. Physics plugin on C2 actually gives more freedom than on CC. I never used SpriteDistorsion on CC so I don't really miss that.
Stuff that neither can do is to edit collision polygons and image points at runtime. For one of my highly moddable game idea that would be very nice feature.
In the end I have still quite pleased to C2, even when I was a bit hesitant to switch to that. Possibility for multiplayer games, multible export options (some issues may occur) and of cource the fact that it is still on development would still keep it as better option for me.